Thermostatic elements



June 21, 1938. F, A, PARSONS 2,121,259

THERMOSTATIC ELEMENTS Original Filed June 26, 1950 INVENTOR M 6?. PM

ATTORNEYS Patented June 21, 1938 UNITED STATES THERMOSTATIC ELEMENTS Fred A. Parsons, Milwaukee, Wis.

Original application June 28, 1930, Serial No. 483,976. Divided and this application May 24, 1934, Serial No. 727,256

11 Claims This invention relates to improvements in thermostatic elements. The present application is a division of my application No. 463,976 filed June 26, 1930.

The object of the invention is to provide a helical form of thermostatic element which will give an axial response and may be made either to expand or to contract its length in response to an increase in temperature.

More particularly stated, it is the purpose of the invention to provide a bimetallic thermostatic element which will give a relatively large response to given temperature change while occupying relatively small space, such response being attributable to the winding of the thermostatic element into helical form and then winding the helix into a larger helical form, the di rection of response being determinable according to which one of the metallic components of go the bimetallic strip is outermost in the original helix.

In the drawing: Figure 1 is a side elevation of a thermostatic I element embodying this invention in association 25 with fragmentary portions shown in axial section of a suitable mounting for the element.

Figure 2 is an enlarged view of the element in end elevation.

Figure 3 is an enlarged detail view in side ele- 30 vation of a single coil element.

Like parts are identified by the same reference characters throughout the several views.

The casing fragmentarily shown at l carries pins 26 and 21 upon which the spring seat member 25 is guided for adjustment under the control of the threaded portion 29 of an adjusting shaft M.

The thermostatically adjusted member 20 is guided for axial movement with reference to the seat member 25 by means of lugs 2l22 engaged in complementary notches 23-44 of the member 25. Members 25 and 20 have anchorage pegs 33 and 34 with which the thermostatic element 32 is engaged .at its ends.

It will be understood that any other suitable mounting may be employed, the mounting illustrated having been reproduced from the drawing of the above entitled parent application for purposes of exemplification only.

The thermostatic element 32 to which this invention particularly pertains, is conveniently made by first winding a minor helix, in this case of relatively small diameter, out of a narrow strip of any well known bimetallic metal, comprising two integrally jolnedstrips or sheets of 'diiierent metals, preferably resilient and necessarily having dlil'erent coeiiicients of thermal expansion. The minor helix or helicoidal member mentioned is so wound that one metal lies outside the coil and the other inside the coil, the different metals being indicated at 35-36 in Figs. 2 and 3.

The minor helix or helicoidal member is then itself axially coiled helically to comprise a major helix wound in the form of a helical spring or peripherally continuous hollow member, as indicated at 32 in Fig. 1. The bimetallic spring so made will expand or contract in the direction of the axis of the major helix when the temperature of the structure is changed.

helix is due to the fact that the winding of the minor helix is such as to produce a torsional or twisting effect along the axis of the minor helix when the temperature changes.

In accordance as the one or the other metal is positioned outside or inside of the minor helix, the major helix will expand or contract along its axis when heated. It may be assumed that reference character 35 indicates the metal having the lesser coeilicient of thermal expansion, while reference character 36 indicates the metal having the greater coeflicient of thermal expansion. It will be noted that the positions of these metals are reversed as between Figs. 2 and 3. The device shown in Fig. 2 will tend to expand axially along its axis when heated, while the device shown in Fig. 3 will contract axially valong the axis of the major helix when heated.

Inasmuch as it is very desirable in some mechamcal installations to have a thermostat which will contract at a rapid rate when heated and will expand correspondingly when cooled, it will be obvious that the disclosed construction has advantages never heretofore realized. Obviously its overall coefllcient of contraction when wound as shown in Fig. 3 is as great as its overall coeflicient of expansion when wound as shown in Fig. 2. In either direction the degree of movement produced inresponse to a given tempera.- ture change is very great in proportion to the amount of space occupied by the element.

I claim:

1. A thermostatic control member comprising a bimetallic strip twisted to form a helicoidal member which is coiled in a generally'helical form.

2. A thermostatic control member comprising a bimetallic strip twisted to form a relatively long helicoidal member of relatively small di- 7 It may be 1 stated that the described result in the major ameter, said helicoidal member being axially coiled to form a peripherally continuous hollow member, the length of which changes with tem perature.

3. A thermostatic element comprising a hollow axially expansible member comprising convolutions of an elongated thermally torsional member, said thermally torsional member comprising a hollow body constituted of a continuous bimetallic strip.

4. As a new article of manufacture, a thermostatic element comprising a bimetallic strip wound to constitute an elongated and substantially helicoidal member in which the metal of said strip having the greater coefllcie'nt of expansion is exposed outwardly, said member being coiled bodily in generally helical form to constitute said element.

5. As a new article of manufacture, a thermostatic element comprising a bimetallic strip wound to constitute an elongated and substantially helicoidal member in which the metal 01' said strip having the lesser coefllcient of ex pansion is exposed outwardly, said member being coiled bodily in generally helical form to constitute said element.

6. A thermostatic element comprising strips of metal of diil'erent coefllcients of thermal expansion rigidly connected along their length and extending progressively about a first axis which in turn is extended progressively about a second axis.

7. A thermostatic element comprising strips of metal of different coefllcients of thermal expansion rigidly connected along their length and extending progressively about a first axis which in turn is extended progressively about a second axis, said strips together comprising a bi-metallic thermostatic spring having an axial thermostatic expansion and contraction together with such resilience as is inherent in the metal oi said strips.

8. A thermostatic element comprising strips 01' metal of different coefiicientsof thermal expansion rigidly connected along their length and extending progressively about a first axis which in turn is extended progressively about a second axis, said strips together comprising a bi-metallic thermostatic spring having an axial thermostatic expansion and contraction together with such resilience as is inherent in the metal of said strips, one of said strips being outside of the other throughout the extent of the spring.

9. An element of the character described, comprising a member in the form of a helix with an open center and subject to torsion when exposed to a changed environmental condition, said memher being bodily formed into convolutions to comprise said element, whereby the twisting of said member occasions a change in the overall length of said element from one end of said convolutlons to the other.

10. As a new article of manufacture, a thermostatic element contractible along its axis when heated and comprising a bimetallic helix elongated in the direction of its axis and composed of a coiled strip of bimetal, the portion of said strip with greater coefllcient of expansion being so disposed that said helix will contract when heated.

11. As a new article of manufacture, a bimetallic helix of axially elongated form comprising a succession of axially progressing coils, at least one of which has at least one loop about an axis transverse with respect to the axis of said coils.

FRED A. PARSONS 

